206 INFLAMMATORY AND SUPPURATIVE CONDITIONS. 



catarrhal there may be great leucocytic emigration. Haemor- 

 rhages also may occur here. 



Besides the two chief types of pneumonia there is another 

 group of cases which are somewhat loosely denominated sep- 

 tic pneumonias, and which may arise in two ways: (i) by the 

 entrance into the trachea and bronchi of discharges, blood, etc., 

 which form a nidus for the growth of septic organisms ; these 

 often set up a purulent capillary bronchitis and lead to infection of 

 the air cells and also of the interstitial tissue of the lung ; (2) from 

 secondary pyogenic infection by means of the blood stream from 

 suppurative foci in other parts of the body. (See Chapter VII., 

 pp. 195 et seq.) In these septic pneumonias various changes, 

 resembling those found in the other types, are often seen round 

 the septic foci. 



In pneumonias, therefore, there may be present a great variety 

 of types of inflammatory reaction. We shall see that with all of 

 them bacteria have been found associated. Special importance 

 is attached to acute croupous pneumonia on account of its course 

 and characters, but reference will also be made to the other 

 forms. 



Historical. Acute lobar pneumonia for long was supposed to be an effect 

 of exposure to cold ; but many observers were dissatisfied with this view 

 of its etiology. Not only did cases occur where no such exposure could be 

 traced, but it had been observed that the disease sometimes occurred epidem- 

 ically, and was occasionally contracted by hospital patients lying in beds 

 adjacent to those occupied by pneumonia cases. Further, the sudden onset 

 and definite course of the disease conformed to the type of an acute infective 

 fever; it was thus suspected by some to be due to a specific infection. This 

 view of its etiology was promulgated by Friedlander, whose results (published 

 in 1882-83) were briefly as follows. In pneumonic lungs there were cocci, 

 adherent usually in pairs, and possessed of a definitely contoured capsule. 

 These cocci could be isolated and grown on gelatin, and on inoculation in 

 mice they produced a kind of septicaemia with inflammation of the serous 

 membranes. The blood and the exudation in serous cavities contained 

 numerous capsulated diplococci. Various criticisms of Friedlander's views 

 soon appeared, the chief being that pneumonia was not produced by him in 

 animals, and there is little doubt that many of the organisms seen by 

 Friedlander were really Fraenkel's pneumococcus, to be presently described. 



By many observers it had been found that the sputum of healthy men,, 

 when injected into animals, sometimes caused death, with the same symptoms 

 as in the case of the injection of Friedlander's coccus ; and in the blood and 

 serous exudations of such animals capsulated diplococci were found. In fact, 

 it was thus first discovered by G. M. Sternberg of Washington, in September, 



